Optical switch for single and multiple projectors

ABSTRACT

A projection system and method therefor comprises a first light source configured to emit a first-eye light, wherein the first-eye light includes a first set of wavelengths; a second light source configured to emit a second-eye light, wherein the second-eye light includes a second set of wavelengths; a first projector including first projection optics configured to receive a first input light; and an optical switch configured to be switched between an a first mode and a second mode, wherein the optical switch is configured to, in the first mode, combine the first-eye light and the second-eye light into a combined light and direct the combined light to the first projection optics as the first input light.

BACKGROUND 1. Field of the Disclosure

This application relates generally to image projection systems andmethods.

2. Description of Related Art

Digital projection systems typically utilize a light source and anoptical system to project an image onto a surface or screen. The opticalsystem may include components such as mirrors, lenses, waveguides,optical fibers, beam splitters, beam combiners, diffusers, spatial lightmodulators (SLMs), and the like.

Some projection systems are capable of three-dimensional (3D)projection; that is, projecting an image onto a screen that can beperceived by a viewer in three dimensions. 3D systems may be designedfor use with dual laser projectors using techniques including spectralseparation. In a spectral separation system, the projector emits lightto provide six primary colors (“primaries”) and the left-eye andright-eye images are separated through spectral filtering. This may beaccomplished by providing the viewer with 3D glasses which include atriple band filter for each eye, such that each eye sees a different RGBspectrum. 3D systems may also be capable of two-dimensional (2D)projection in some modes; that is, projecting an image onto a screenthat is perceived by a viewer in two dimensions.

When using a 3D projection system to project 2D images, comparativeexamples utilize the dual projectors of the 3D projection system ineither a stacked or side-by-side arrangement with some minimum distancebetween the projectors, and their projected images are overlaid at thescreen. However, because there exists a minimum distance between thedual projectors of the comparative example systems and there aremanufacturing variations between the optical components of the twoprojectors, such systems may suffer from image differences which preventperfectly overlaying the two images.

BRIEF SUMMARY OF THE DISCLOSURE

Various aspects of the present disclosure relate to projection systemsand methods that may be optically switched between 3D projection and 2Dprojection modes and, when in the 2D projection modes, do not exhibitkeystone artifacts.

In one exemplary aspect of the present disclosure, there is provided aprojection system comprising: a first light source configured to emit afirst-eye light, wherein the first-eye light includes a first set ofwavelengths; a second light source configured to emit a second-eyelight, wherein the second-eye light includes a second set ofwavelengths; a first projector including first projection opticsconfigured to receive a first input light; and an optical switchconfigured to be switched between an a first mode and a second mode,wherein the optical switch is configured to, in the first mode, combinethe first-eye light and the second-eye light into a combined light anddirect the combined light to the first projection optics as the firstinput light.

In another exemplary aspect of the present disclosure, there is provideda method of image projection comprising: emitting a first-eye light by afirst light source, wherein the first-eye light includes a first set ofwavelengths; emitting a second-eye light by a second light source,wherein the second-eye light includes a second set of wavelengths;receiving a first input light by a first projector including firstprojection optics; and switching an optical switch between an a firstmode and a second mode, wherein the optical switch is configured to, inthe first mode, combine the first-eye light and the second-eye lightinto a combined light and direct the combined light to the firstprojection optics as the first input light.

In this manner, various aspects of the present disclosure provide forthe projection display of light using a system that may be switchedbetween 2D operation and 3D operation, and that does not exhibitkeystone artifacts in 2D operation. Thus, various aspects of the presentdisclosure effect improvements in at least the technical fields of imageprojection, cinematography, signal processing, and the like.

DESCRIPTION OF THE DRAWINGS

These and other more detailed and specific features of variousembodiments are more fully disclosed in the following description,reference being had to the accompanying drawings, in which:

FIG. 1 illustrates a block diagram of an exemplary projection systemaccording to various aspects of the present disclosure;

FIGS. 2A-2B illustrate exemplary projector details for the projectionsystem according to FIG. 1 ;

FIG. 3 illustrates a block diagram of another exemplary projectionsystem according to various aspects of the present disclosure;

FIGS. 4A-4B illustrate exemplary projector details for the projectionsystem according to FIG. 3 ;

FIG. 5 illustrates a block diagram of another exemplary projectionsystem according to various aspects of the present disclosure;

FIGS. 6A-6B illustrate exemplary projector details for the projectionsystem according to FIG. 5 ; and

FIG. 7 illustrates an exemplary device implementing various aspects ofthe present disclosure.

DETAILED DESCRIPTION

This disclosure and aspects thereof can be embodied in various forms,including hardware or circuits controlled by computer-implementedmethods, computer program products, computer systems and networks, userinterfaces, and application programming interfaces; as well ashardware-implemented methods, signal processing circuits, memory arrays,application specific integrated circuits, field programmable gatearrays, and the like. The foregoing summary is intended solely to give ageneral idea of various aspects of the present disclosure, and does notlimit the scope of the disclosure in any way.

In the following description, numerous details are set forth, such asspectra, timings, operations, and the like, in order to provide anunderstanding of one or more aspects of the present disclosure. It willbe readily apparent to one skilled in the art that these specificdetails are merely exemplary and not intended to limit the scope of thisapplication.

Moreover, while the present disclosure focuses mainly on examples inwhich the various elements are used in digital projection systems, itwill be understood that this is merely one example of an implementation.It will further be understood that the disclosed systems and methods canbe used in any device in which there is a need to project light; forexample, cinema, consumer and other commercial projection systems,optical communications, heads-up displays, virtual reality displays, andthe like.

Projection Systems

In some implementations, projection systems (e.g., certain digitalcinema laser projection systems) use two projectors to selectivelyimplement both 2D and stereoscopic 3D modes of operation. For example,such a 3D projection system includes two projectors that, when operatingin a 3D mode, continuously project a left-eye image and a right-eyeimage each including three primaries, respectively. In a 2D mode, thetwo projectors playback the same content and the images are overlaid atthe screen, such that the resultant image includes six primaries.

As noted above, comparative examples of 3D projection systems whichinclude a 2D mode may utilize both projectors and overlay the respectiveimages on a screen, thereby to enhance brightness and contrast. Becausethere is some minimum distance between the projection lenses of the twoprojectors in comparative example systems (vertically where the twoprojectors are stacked, or horizontally where the two projectors areside-by-side), such comparative example systems exhibit mirroredkeystone artifacts (i.e., portions of the projected image that do notoverlap, and thus are perceived by the viewer as a “double image”) inthe 2D mode as a result of the distance between the two projectors.Also, even if the two projectors are matched as closely as possible,manufacturing variations in the projection lens and other optical partsmay make differences between the two images that prevent an acceptableoverlay.

Comparative methods to remedy these defects may be complicated and/orcostly. For example, the use of pixel warping to remedy the defectsrequires sophisticated optical hardware and custom software solutions.Although such systems may work under particular conditions, anyprojector movement will result in overlay defects reappearing. Even ifthe warping routine is performed on a regular basis in view of potentialmovement, the routine may take up to 30 minutes and requires projectionsystems to be warmed to operating temperature to ensure no subsequentthermal drift. In any event, pixel warping is strongly objected to bymany movie studios and other content creators (especially during themovie mastering and grading process) because it alters the content.

Projection systems according to various aspects of the presentdisclosure are described with respect to dual laser projectorsimplementing a spectral separation technique; however, the presentdisclosure may also be implemented using other light sources such aslamps. Because laser light sources are low-etendue sources, the lightbeams emitted therefrom can be efficiently formed into collimated beamsand guided through various optical components of the projection system,such as the optical switch described in more detail below. Each laserprojector may provide three of the six primaries. When operating in the2D mode, all six primaries are projected onto the screen to create asingle image that may be viewed by the viewer (e.g., an audience memberin a theater) as a 2D image. When operating in the 3D mode, the sets ofthree primaries from each laser projector are projected onto the screento create a left-eye image and a right-eye image, respectively, and theleft-eye and right-eye images are separated through spectral filteringand separately provided to the left and right eyes of the viewer. Inthis manner, the viewer perceives the projected image as a 3D image.

In order to view the projected image in three dimensions, the viewer maybe provided with glasses having optical filters therein. For example,the glasses may have a left optical filter disposed over the viewer'sleft eye and configured to pass light intended for the left eye theretowhile blocking light intended for the right eye, and may have a rightoptical filter disposed over the viewer's right eye and configured topass light intended for the right eye thereto while blocking lightintended for the left eye. To operate thusly, the left optical filterand the right optical filter have different acceptance bands.Differences in the image presented to the viewers left and right eyescause the projected images to appear 3D.

To eliminate the keystone artifacts or other deleterious effects thatexist in comparative examples of 3D-capable projection systems in 2Doperation, various aspects of the present disclosure include an opticalswitch that combines light from both emission sources into oneprojector. For 3D operation, the optical switch is configured such thatthe light from each emission source is respectively fed into itscorresponding projector. The optical switch can either be a combiner ora splitter. Theaters that predominantly exhibit 2D content will benefitfrom reduced hours accumulated on the secondary projector because itwill only be used for 3D operation.

Optical Switch—Combiner

For projection systems in which each set of lasers is delivered overindependent fiber optics, the optical switch is a combiner. Thisconfiguration allows all light from both left- and right-eye sets oflasers to be switched into one projector in a first mode (e.g., for 2Doperation), or each set of laser outputs to be switched to eachprojector respectively in a second mode (e.g., for 3D operation). In anexemplary digital cinema laser projection system, the two sets of lasershave different nominal primary wavelengths (e.g., R1, G1, and B1 for onelaser and R2, G2, and B2 for the other laser) with a wavelengthseparation of about 10-30 nm between corresponding primaries. A coatingon a flat optic may be designed to reflect one set of RGB wavelengthsand pass the other set of RGB wavelengths. With this combiner opticpositioned in the beam path, the beams can be overlapped and combinedbefore launching into the projection system for single-projector 2Doperation. With the combiner optic moved out of the beam path, each RGBset is delivered appropriately to each projector for 3D operation. Themovement of the combiner optic may be manual or automated on a rotatingor translating mechanism. FIG. 1 illustrates an exemplary implementationof such a system.

In particular, FIG. 1 illustrates a projection system 10 which includesa first laser light source 100L which outputs a first set of wavelengths(e.g., three primaries) corresponding to left-eye light and a secondlaser light source 100R which outputs a second set of wavelengths (e.g.,three primaries) corresponding to right-eye light. The first laser lightsource 100L is, for example, a first plurality of laser emitters (e.g.,fiber lasers, laser diodes, or combinations thereof) which output lightvia an optical fiber which terminates in a first optical coupler 111.Alternatively, each (or subsets) of the primaries corresponding to theleft-eye light may be output via a separate optical fiber whichterminates in the first optical coupler 111, or in a plurality of firstoptical couplers 111. The second laser light source 100R is, forexample, a second plurality of laser emitters (e.g., fiber lasers, laserdiodes, or combinations thereof) which output light via a separateoptical fiber which terminates in a second optical coupler 112.Alternatively, each (or subsets) of the primaries corresponding to theright-eye light may be output via a separate optical fiber whichterminates in the second optical coupler 112, or in a plurality ofsecond optical couplers 112. The first laser light source 100L and thesecond laser light source 100R may be disposed in independent cabinetsor may be consolidated into one cabinet. The projection system 10includes a first projector 120L which, in a 3D mode of the projectionsystem, projects a left-eye image. The projection system 10 furtherincludes a second projector 120R. In the 3D mode, the second projector120R projects a right-eye image. In a 2D mode, the second projector 120Rprojects all six primaries as a single image.

Both the first optical coupler 111 and the second optical coupler 112are optically connected to the second projector 120R. Light from thefirst optical coupler 111 and the second optical coupler 112respectively follow a first optical path 131 and a second optical path132 to a first optical system 121, which selectively operates as anoptical switch and right-eye filter. Depending on the state of theoptical switch, the first optical system 121 may direct a portion of thereceived light to a third optical coupler 122 for further opticalprocessing as will be described in more detail below. Moreover,depending on the state of the optical switch, the first optical system121 may direct all or a portion of the received light via a thirdoptical path 141 to first projection optics 123. The first projectionoptics 123 project an image via a first output optical path 151.

When the state of the optical switch is such that a portion of thereceived light is directed to the third optical coupler 122, the lightis transported via an optical fiber to a fourth optical coupler 125associated with the second projector 120L. The optical fiber may be asingle fiber or a multi-fiber bundle. The second projector 120L includesa second optical system 124, which operates as a left-eye filter. Lightfrom the second optical system 124 is directed via a fourth optical path142 to second projection optics 126. The second projection optics 126project an image via a second output optical path 152. The firstprojection optics 123 and the second projection optics 126 includeoptical components such as light homogenizers (e.g., integrating rods,fly's-eye optical components, and combinations thereof), lenses (e.g.,Fourier transform lenses, zoom lens arrays, projection lenses, andcombinations thereof), mirrors, SLMs (e.g., digital micromirror devices(DMDs)), and so on.

When the projection system 10 is in a 2D mode, the optical switch of thefirst optical system 121 is configured to direct all six primaries tothe first projection optics 123. Thus, the image output via the firstoutput optical path 151 corresponds to a six-primary 2D image. When theprojection system 10 is in a 3D mode, the optical switch of the firstoptical system 121 is configured to direct the three primaries emittedby the first laser light source 100L to the second projection optics 126and to direct the three primaries emitted by the second laser lightsource 100R to the first projection optics 123. Thus, the image outputvia the second output optical path 152 corresponds to a three-primaryleft-eye image and the image output via the first output optical path151 corresponds to a three-primary right-eye image.

FIGS. 2A-2B illustrate the modes of the projection system 10 in greaterdetail. In particular, FIG. 2A illustrates a part of the projectionsystem 10 in the 2D mode, and FIG. 2B illustrates the part of theprojection system 10 in the 3D mode. As illustrated in FIGS. 2A-2B, thefirst optical system 121 includes a first lens 201, a second lens 202, athird lens 203, a fourth lens 204, a movable mirror 211 (or otherreflective element), and a first filter 212. The second optical system124 includes a fifth lens 205, a second filter 213, and a sixth lens206. In some examples, the first filter 212 and the second filter 213are trim filters that reflect unwanted tails of the emission peaks. Themovable mirror 211 is movable between a position in the beam path and aposition out of the beam path. The movement of the movable mirror 211may be manual or automated on a rotating or translating mechanism.

When the projection system 10 is in the 2D mode illustrated in FIG. 2A,the movable mirror 211 is located in an optical path of light receivedvia the first optical coupler 111 through the first lens 201. In thismode, the movable mirror 211 reflects the light from the first opticalcoupler 111 toward the first filter 212. The first filter 212 acts bothas a combiner and as a trim filter. The first filter 212 is located inan optical path of light received via the second optical coupler 112through the second lens 202 and reflects a portion of the lightcorresponding to unwanted light (e.g., unwanted tails of the emissionbands) from the second laser light source 100R while transmitting aportion of the light corresponding to the desired light from the secondlaser light source 100R. While the first filter 212 is illustrated as arelatively-thick element, in practice the first filter 212 (and/or otherfilters illustrated and described herein) may be sufficiently thin thatthe transmitted and reflected beams are substantially overlapping,thereby to improve uniformity. The first filter 212 is also located inan optical path of light reflected by the movable mirror 211 in the 2Dmode, such that the transmitted right-eye light and the doubly-reflectedleft-eye light travel along the same (or substantially the same) opticalpath through the fourth lens 204 and to the first projection optics 123.As illustrated, this optical path corresponds to the third optical path141 of FIG. 1 . Thus, in the 2D mode, the first projection optics 123output an image along the first output optical path 151 whichcorresponds to a six-primary 2D image exhibiting reduced or no overlayartifacts.

When the projection system 10 is in the 3D mode illustrated in FIG. 2B,the movable mirror 211 is located outside of the optical path of lightreceived via the first optical coupler 111 through the first lens 201.Thus, the light from the first optical coupler 111 proceeds through thethird lens 203 and into the third optical coupler 122, where it istransported via an optical fiber to the fourth optical coupler 125associated with the second projector 120L. The light from the secondoptical coupler 112 passes through the second lens 202 to the firstfilter 212, where the portion of the light corresponding to unwantedlight (e.g., unwanted tails of the emission bands) from the second laserlight source 100R is reflected and the portion of the lightcorresponding to the desired light from the second laser light source100R is transmitted through the fourth lens 204 and to the firstprojection optics 123.

In the second projector 120L, the light input by the fourth opticalcoupler 125 passes through the fifth lens 205 to the second filter 213.The second filter 213 is a trim filter that reflects a portion of thelight corresponding to unwanted tails of the emission bands from thefirst laser light source 100L while transmitting a portion of the lightcorresponding to the desired peaks from the first laser light source100L. The transmitted portion passes through the sixth lens 206 andtravels along an optical path (as illustrated, corresponding to thefourth optical path 142 of FIG. 1 ) to the second projection optics 126.Thus, in the 3D mode the first projection optics 123 output an imagealong the first output optical path 151 which corresponds to athree-primary right-eye image and the second projection optics 126output an image along the second output optical path 152 whichcorresponds to a three-primary left-eye image.

The combiner configuration of the optical switch allows left and righttrim filters (i.e., the first filter 212 and the second filter 213) tobe present in both 2D and 3D operation. In 2D operation, this ensuresdefined spectra to meet color gamut specifications, even with lasersthat may contain emission that is out of band. In 3D operation, thiseliminates unwanted spectral bands from each projector respectively, andthereby reduces crosstalk between the eyes.

While FIGS. 2A-2B illustrate the optical switch as combining theleft-eye and right-eye light by reflecting the left-eye light andcombining it with the right-eye light in the 2D mode, the presentdisclosure is not so limited. In some implementations, the movablemirror 211 and the first filter 212 may be reversed, and appropriateadjustments may be made to the angle and axial position of the remainingoptical components, so that the optical switch reflects the right-eyelight and combines it with the left-eye light in the 2D mode. Bylocating the combiner inside the projector 120R, there is no need torelaunch light from the combiner into a fiber patch cable. However,while FIGS. 2A-2B illustrate the combiner as being internal to thesecond projector 120R, the present disclosure is not so limited. In someimplementations, the combiner may be externally located with fiber patchcables to each projector. The fiber patch cables between an externalswitch and the projectors may be selected to accommodate differentdistances between the switch and projectors, thereby allowing thedistance from the lasers to the external shift to be made a standardlength.

Moreover, while FIGS. 1-2B illustrate the first projector 120L and thesecond projector 120R using separate blocks, the present disclosure isnot limited to implementations where the first projector 120L and thesecond projector 120R are confined to separate cabinets or casings. Insome implementations, the first projector 120L and the second projector120R may be included in a single projector cabinet from which the firstprojection optics 123 and (in the 3D mode) the second projection optics126 output their respective images, the fiber patch cable between thethird optical coupler 122 and the fourth optical coupler 125 (as well asthe couplers themselves) may be eliminated.

Optical Switch—Splitter

For projection systems in which both sets of lasers are delivered over asingle fiber optic, the optical switch may be a splitter. Thisconfiguration allows all light from both left- and right-eye sets oflasers to be switched into one projector in a first mode (e.g., for 2Doperation), or each set of laser outputs to be switched to eachprojector respectively in a second mode (e.g., for 3D operation). Asnoted above, in an exemplary digital cinema laser projection system, thetwo sets of lasers have different nominal primary wavelengths (e.g., R1,G1, and B1 for one laser and R2, G2, and B2 for the other laser) with awavelength separation of about 10-30 nm between corresponding primaries.A coating on a flat optic may be designed to reflect one set of RGBwavelengths and pass the other set of RGB wavelengths. With thissplitter optic positioned in the beam path, one set of wavelengths ispassed to one projector and the other set of wavelengths is reflected tothe other projector for two-projector 3D operation. With the splitteroptic moved out of the beam path, both sets of RGB wavelengths aredelivered to one projector for single-projector 2D operation. Themovement of the splitter optic may be manual or automated on a rotatingor translating mechanism. FIG. 3 illustrates an exemplary implementationof such a system.

In particular, FIG. 3 illustrates a projection system 30 which includesa laser light source 300 which outputs a combined set of wavelengths(e.g., six primaries) corresponding to both a first subset ofwavelengths for left-eye light and a second subset of wavelengths forright-eye light. The laser light source 300 is, for example, a pluralityof laser emitters (e.g., fiber lasers, laser diodes, or combinationsthereof) which output light via an optical fiber which terminates in afirst optical coupler 310. Alternatively, each (or subsets) of the sixprimaries may be output via a separate optical fiber which terminates inthe first optical coupler 310, or in a plurality of first opticalcouplers 310. The projection system 50 includes a first projector 320Lwhich, in a 3D mode of the projection system, projects a left-eye image.The projection system 30 further includes a second projector 320R. Inthe 3D mode, the second projector 320R projects a right-eye image. In a2D mode, the second projector 320R projects all six primaries a singleimage.

The optical coupler 310 is optically connected to the second projector320R. Light from the optical coupler 310 follows a first optical path330 to a first optical system 321, which selectively operates both as anoptical switch and as a right-eye filter. Depending on the state of theoptical switch, the first optical system 321 may direct a portion of thereceived light to a second optical coupler 322 for further opticalprocessing as will be described in more detail below. Moreover,depending on the state of the optical switch, the first optical system321 may direct all or a portion of the received light via a secondoptical path 341 to first projection optics 323. The first projectionoptics 323 project an image via a first output optical path 351.

When the state of the optical switch is such that a portion of thereceived light is directed to the second optical coupler 322, the lightis transported via an optical fiber to a third optical coupler 325associated with the second projector 320L. The optical fiber may be asingle fiber or a multi-fiber bundle. The second projector 320L includesa second optical system 324, which operates as a left-eye filter. Lightfrom the second optical system 324 is directed via a third optical path342 to second projection optics 326. The second projection optics 326project an image via a second output optical path 352. The firstprojection optics 323 and the second projection optics 326 includeoptical components such as light homogenizers (e.g., integrating rods,fly's-eye optical components, and combinations thereof), lenses (e.g.,zoom lens arrays, projection lenses, and combinations thereof), mirrors,SLMs (e.g., DMDs), and so on.

When the projection system 30 is in a 2D mode, the optical switch of thefirst optical system 321 is configured to direct all six primaries tothe first projection optics 323. Thus, the image output via the firstoutput optical path 351 corresponds to a six-primary 2D image. When theprojection system 30 is in a 3D mode, the optical switch of the firstoptical system 321 is configured to direct the three primariescorresponding to the left-eye image emitted by the laser light source300 to the second projection optics 326 and to direct the threeprimaries corresponding to the right-eye image emitted by the laserlight source 300 to the first projection optics 323. Thus, the imageoutput via the second output optical path 352 corresponds to athree-primary left-eye image and the image output via the first outputoptical path 351 corresponds to a three-primary right-eye image.

FIGS. 4A-4B illustrate the modes of the projection system 30 in greaterdetail. In particular, FIG. 4A illustrates a part of the projectionsystem 30 in the 2D mode, and FIG. 4B illustrates the part of theprojection system 30 in the 3D mode. As illustrated in FIGS. 4A-4B, thefirst optical system 321 includes a first lens 401, a second lens 402, amovable first filter 411, and a mirror 412 (or other reflectiveelement). The second optical system 324 includes a third lens 403, asecond filter 413, and a fourth lens 404. In some examples, the firstfilter 411 and the second filter 413 are trim filters that reflectunwanted tails of the emission peaks. The first filter 411 is movablebetween a position in the beam path and a position out of the beam path.The movement of the first filter 411 may be manual or automated on arotating or translating mechanism.

When the projection system 30 is in the 2D mode illustrated in FIG. 4A,the first filter 411 is located outside of the optical path of lightreceived via the first optical coupler 310 through the first lens 401.Thus, all (or substantially all) of the light from the first opticalcoupler 310 proceeds along the second optical path 341 and to the firstprojection optics 423. Thus, in the 2D mode, the first projection optics423 output an image along the first output optical path 351 whichcorresponds to a six-primary 2D image exhibiting reduced or no overlayartifacts.

When the projection system 30 is in the 3D mode illustrated in FIG. 4B,the first filter 411 is located in the optical path of light receivedvia the optical coupler 310 through the first lens 401. The first filter411 acts as a splitter and as a trim filter. The first filter reflects aportion of the light corresponding to the left-eye image emitted by thelaser light source 300 and a portion of the light corresponding tounwanted tails of the emission bands for the right-eye image emitted bythe laser light source 300, while transmitting a portion of the lightcorresponding to the desired peaks of the right-eye image from the laserlight source 300. In the particular example illustrated in FIG. 4B, themirror 412 is located in an optical path of the reflected portion oflight, and reflects the incident light through the second lens 402 tothe second optical coupler 322, where it is transported via an opticalfiber to the third optical coupler 325 associated with the secondprojector 320L. In other examples, the mirror 412 may be omitted, inwhich case the second optical coupler 322 may be repositioned such thatit lies in the optical path of the reflected portion of light.

In the second projector 320L, the light input by the third opticalcoupler 325 passes through the third lens 403 to the second filter 413.The second filter 413 is a trim filter that reflects a portion of thelight corresponding to unwanted light of both the left-eye and right-eyeemission bands from the laser light source 300 while transmitting aportion of the light corresponding to the desired peaks of the left-eyeimage from the laser light source 300. The transmitted portion passesthrough the fourth lens 404 and travels along an optical path (asillustrated, corresponding to the fourth optical path 342 of FIG. 3 ) tothe second projection optics 326. Thus, in the 3D mode the firstprojection optics 323 output an image along the first output opticalpath 351 which corresponds to a three-primary right-eye image and thesecond projection optics 326 output an image along the second outputoptical path 352 which corresponds to a three-primary left-eye image.

In the particular illustration of FIGS. 4A-4B, refraction of lighttransmitted through the first filter 411 may cause the optical axis ofthe second optical path 341 to shift laterally. In the event that such ashift negatively affects the performance of the first projection optics323, one or more optical elements such as an electronic crystal may bedisposed between the first filter 411 and the first projection optics323 to provide an equal and opposite lateral shift to the optical axisof the second optical path 341. Where such optical elements are used,they may be configured to move along with the first filter 411 so thatthey do not affect light in the 2D mode.

While FIGS. 4A-4B illustrate the optical switch as splitting theleft-eye and right-eye light such that the left-eye light is sent to aseparate projector in the 3D mode, the present disclosure is not solimited. In some implementations, the filtering and reflectionwavelengths of the first filter 411 may be appropriately chosen suchthat the right-eye light is sent to a separate projector in the 3D mode.By locating the splitter inside the projector 120R, there is no need torelaunch light from the splitter into a fiber patch cable. However,while FIGS. 4A-4B illustrate the splitter as being internal to thesecond projector 420R, the present disclosure is not so limited. In someimplementations, the splitter may be externally located with fiber patchcables to each projector. The fiber patch cables between an externalswitch and the projectors may be selected to accommodate differentdistances between the switch and projectors, thereby allowing thedistance from the lasers to the external shift to be made a standardlength.

Moreover, while FIGS. 3-4B illustrate the first projector 320L and thesecond projector 320R using separate blocks, the present disclosure isnot limited to implementations where the first projector 320L and thesecond projector 320R are confined to separate cabinets or casings. Insome implementations, the first projector 320L and the second projector320R may be included in a single projector cabinet from which the firstprojection optics 323 and (in the 3D mode) the second projection optics326 output their respective images, the fiber patch cable between thethird optical coupler 322 and the fourth optical coupler 325 (as well asthe couplers themselves) may be eliminated.

Optical Switch—Splitter/Recombiner

For projection systems in which both sets of lasers are delivered over asingle fiber optic, the optical switch may alternatively be asplitter/recombiner. This configuration similarly allows all light fromboth left- and right-eye sets of lasers to be switched into oneprojector in a first mode (e.g., for 2D operation), or each set of laseroutputs to be switched to each projector respectively in a second mode(e.g., for 3D operation); however, this configuration may result in areduced or eliminated launch offset (lateral shift) as compared to thesplitter configuration discussed above. Moreover, this configuration mayresult in eased manufacturing tolerances and/or reduced precisionrequirements for the positioning of various components.

As noted above, in an exemplary digital cinema laser projection system,the two sets of lasers have different nominal primary wavelengths (e.g.,R1, G1, and B1 for one laser and R2, G2, and B2 for the other laser)with a wavelength separation of about 10-30 nm between correspondingprimaries. A coating on a flat optic may be designed to reflect one setof RGB wavelengths and pass the other set of RGB wavelengths. With arecombiner portion of the splitter/recombiner optic positioned in thebeam path, one set of wavelengths is passed to one projector and theother set of wavelengths is reflected to the other projector fortwo-projector 3D operation. With the recombiner portion of thesplitter/recombiner optic moved out of the beam path, both sets of RGBwavelengths are delivered to one projector for single-projector 2Doperation. The movement of the recombiner portion may be manual orautomated on a rotating or translating mechanism. FIG. 5 illustrates anexemplary implementation of such a system.

In particular, FIG. 5 illustrates a projection system 50 which includesa laser light source 500 which outputs a combined set of wavelengths(e.g., six primaries) corresponding to both a first subset ofwavelengths for left-eye light and a second subset of wavelengths forright-eye light. The laser light source 500 is, for example, a pluralityof laser emitters (e.g., fiber lasers, laser diodes, or combinationsthereof) which output light via an optical fiber which terminates in afirst optical coupler 510. Alternatively, each (or subsets) of the sixprimaries may be output via a separate optical fiber which terminates inthe first optical coupler 510, or in a plurality of first opticalcouplers 510. The projection system 50 includes a first projector 520Lwhich, in a 3D mode of the projection system, projects a left-eye image.The projection system 50 further includes a second projector 520R. Inthe 3D mode, the second projector 520R projects a right-eye image. In a2D mode, the second projector 520R projects all six primaries a singleimage.

The optical coupler 510 is optically connected to the second projector520R. Light from the optical coupler 510 follows a first optical path530 to a first optical system 521, which selectively operates both as anoptical switch and as a right-eye filter. Depending on the state of theoptical switch, the first optical system 521 may direct a portion of thereceived light to a second optical coupler 522 for further opticalprocessing as will be described in more detail below. Moreover,depending on the state of the optical switch, the first optical system521 may direct all or a portion of the received light via a secondoptical path 541 to first projection optics 523. The first projectionoptics 523 project an image via a first output optical path 551.

When the state of the optical switch is such that a portion of thereceived light is directed to the second optical coupler 522, the lightis transported via an optical fiber to a third optical coupler 525associated with the second projector 520L. The optical fiber may be asingle fiber or a multi-fiber bundle. The second projector 520L includesa second optical system 524, which operates as a left-eye filter. Lightfrom the second optical system 524 is directed via a third optical path542 to second projection optics 526. The second projection optics 526project an image via a second output optical path 552. The firstprojection optics 523 and the second projection optics 526 includeoptical components such as light homogenizers (e.g., integrating rods,fly's-eye optical components, and combinations thereof), lenses (e.g.,zoom lens arrays, projection lenses, and combinations thereof), mirrors,SLMs (e.g., DMDs), and so on.

When the projection system 50 is in a 2D mode, the optical switch of thefirst optical system 521 is configured to direct all six primaries tothe first projection optics 523. Thus, the image output via the firstoutput optical path 551 corresponds to a six-primary 2D image. When theprojection system 50 is in a 3D mode, the optical switch of the firstoptical system 521 is configured to direct the three primariescorresponding to the left-eye image emitted by the laser light source500 to the second projection optics 526 and to direct the threeprimaries corresponding to the right-eye image emitted by the laserlight source 500 to the first projection optics 523. Thus, the imageoutput via the second output optical path 552 corresponds to athree-primary left-eye image and the image output via the first outputoptical path 551 corresponds to a three-primary right-eye image.

FIGS. 6A-6B illustrate the modes of the projection system 50 in greaterdetail. In particular, FIG. 6A illustrates a part of the projectionsystem 50 in the 2D mode, and FIG. 6B illustrates the part of theprojection system 50 in the 3D mode. As illustrated in FIGS. 6A-6B, thefirst optical system 521 includes a first lens 601, a second lens 602, athird lens 603, a first filter 611, a second filter 612, a stationarymirror 613 (or other reflective element), and a movable mirror 614. Thesecond optical system 524 includes a fourth lens 604, a fifth lens 605,and a third filter 615. In some examples, the first filter 611, thesecond filter 612, and the third filter 615 are trim filters thatreflect unwanted tails of the emission peaks. The movable mirror 614 ismovable between a position in a section of the beam path and a positionout of the section of the beam path. The movement of the movable mirror614 may be manual or automated on a rotating or translating mechanism.

Light received from the first optical coupler 510 through the first lens601 is incident on the first filter 611. The first filter 611 reflects aportion of the light corresponding to the left-eye image emitted by thelaser light source 500, while transmitting a portion of the lightcorresponding to the desired peaks of the right-eye image from the laserlight source 500 toward a first surface of the second filter 612. Thesecond filter 612 reflects a portion of the light that has passedthrough the first filter 611 corresponding to unwanted tails of theemission bands for the right-eye image emitted by the laser light source500, while transmitting a portion of the light corresponding to thedesired peaks of the right-eye image from the laser light source 500.

Light reflected by the first filter 611 is incident on the stationarymirror 613. When the projection system 50 is in the 2D mode illustratedin FIG. 6A, the movable mirror 614 is located in the optical path oflight reflected from the stationary mirror 613. In this mode, themovable mirror 614 reflects the light reflected from the stationarymirror 613 toward a second surface of the second filter 613 opposite thefirst surface. The second filter 613 reflects the light reflected fromthe movable mirror 614 toward the second lens 602, such that thetransmitted right-eye light and the triply-reflected left-eye lighttravel along the same (or substantially the same optical path throughthe second lens 602 and to the first projection optics 523. Becausethese optical paths are the same (or substantially the same), the firstoptical system 521 corrects for lateral shift. As illustrated, thisoptical path corresponds to the third optical path 541 of FIG. 5 . Thus,in the 2D mode, the first projection optics 523 output an image alongthe first output optical path 551 which corresponds to a six-primary 2Dimage exhibiting reduced or no overlay artifacts or lateral shift.

When the projection system 50 is in the 3D mode illustrated in FIG. 6B,the movable mirror 614 is located outside of the optical path of thelight reflected by the stationary mirror 613. In this mode, the lightreflected by the stationary mirror 613 proceeds through the third lens603 and into the second optical coupler 522, where it is transported viaan optical fiber to the fourth optical coupler 525 associated with thesecond projector 520L. In the second projector 520L, the light input bythe fourth optical coupler 525 passes through the fourth lens 604 to thethird filter 615. The third filter is a trim filter that reflects aportion of the light corresponding to unwanted tails of the emissionbands of from the laser light source 500 while transmitting a portion ofthe light corresponding to the desired peaks from the laser light source500. The transmitted portion passes through the fifth lens 605 andtravels along an optical path (as illustrated, corresponding to thefourth optical path 542 of FIG. 5 ) to the second projection optics 526.

Meanwhile, the light transmitted through the first filter 611 (and notreflected toward the stationary mirror 613) is incident on the firstsurface of the second filter 612. As in the 2D mode, the second filter612 reflects a portion of the light that has passed through the firstfilter 611 corresponding to unwanted tails of the emission bands for theright-eye image emitted by the laser light source 500, whiletransmitting a portion of the light corresponding to the desired peaksof the right-eye image from the laser light source 500 through thesecond lens 602 and to the first projection optics 523. Thus, in the 3Dmode the first projection optics 523 outputs an image along the firstoutput optical path 551 which corresponds to a three-primary right-eyeimage and the second projection optics output an image along the secondoutput optical path 552 which corresponds to a three-primary left-eyeimage.

While FIG. 6B illustrates the second filter 612 as reflecting theportion of the light that has passed through the first filter 611corresponding to unwanted tails of the emission bands for the right-eyeimage emitted by the laser light source 500, the present disclosure isnot so limited. In other implementations, the first filter 611 reflectsthe unwanted tails of the emission bands for the right-eye image emittedby the laser light source 500 in addition to the portion of the lightcorresponding to the left-eye image emitted by the laser light source500, such that the third filter 615 reflects a portion of the lightcorresponding to unwanted light of both the left-eye and right-eyeemission bands from the laser light source 500 while the projectionsystem 50 is in the 3D mode.

Furthermore, while FIGS. 6A-6B illustrate the optical switch assplitting the left-eye and right-eye light such that the left-eye lightis sent to a separate projector in the 3D mode, the present disclosureis not so limited. In some implementations, the filtering and reflectionwavelengths of the first filter 611 or the second filter 612 may beappropriately chosen such that the right-eye light is sent to a separateprojector in the 3D mode. By locating the splitter/recombiner inside theprojector 520R, there is no need to relaunch light from thesplitter/recombiner into a fiber patch cable. However, while FIGS. 6A-6Billustrate the splitter/recombiner as being internal to the secondprojector 520R, the present disclosure is not so limited. In someimplementations, the splitter/recombiner may be externally located withfiber patch cables to each projector. The fiber patch cables between anexternal switch and the projectors may be selected to accommodatedifferent distances between the switch and projectors, thereby allowingthe distance from the lasers to the external shift to be made a standardlength.

Moreover, while FIGS. 5-6B illustrate the first projector 520L and thesecond projector 520R using separate blocks, the present disclosure isnot limited to implementations where the first projector 520L and thesecond projector 520R are confined to separate cabinets or casings. Insome implementations, the first projector 520L and the second projector520R may be included in a single projector cabinet from which the firstprojection optics 523 and (in the 3D mode) the second projection optics526 output their respective images, the fiber patch cable between thethird optical coupler 522 and the fourth optical coupler 525 (as well asthe couplers themselves) may be eliminated.

Device Implementation

Projection systems including the above-described optical switch may beimplemented by way of an electronic device including several optical andelectronic components. FIG. 7 illustrates one such device 700.

As illustrated in FIG. 7 , the device 700 includes a projection system710, a controller 720, a memory 730, and communications and I/Ocircuitry 740. The projection system 710, the controller 720, the memory730, and the communications and I/O circuitry 740 communicate via a bus750. The projection system 710 may be, for example, the projectionsystem 10 illustrated in FIG. 1 , the projection system 30 illustratedin FIG. 3 , or the projection system 50 illustrated in FIG. 5 . Thecontroller 720 may be, for example, one or more processors or othercontrol circuitry, such as a central processing unit (CPU), a graphicsprocessing unit (GPU), a field-programmable gate array (FPGA), anapplication-specific integrated circuit (ASIC), and the like. The memory730 may be, for example, a hard disk, a removable media drive, anoptical or magnetic storage device, and combinations thereof. The memory730 may include read-only memory (ROM) and/or random-access memory(RAM). The communications and I/O circuitry 740 may be, for example, aset of circuits, ports, connectors, etc., to allow the device 700 tocommunicate with a user or another device. The communications and I/Ocircuitry 740 may include wired communication interfaces and connect touser interface devices such as a mouse, a keyboard, a display, a touchscreen, a wired network, and so on; additionally or alternatively, thecommunications and I/O circuitry 740 may include wireless communicationinterfaces such as Bluetooth, near-field communications (NFC), wirelesslocal area networks (WLANs), and so on. The communications and I/Ocircuitry 740 may allow for the receipt of user instructions, streamingimage data, device calibration, software or firmware updates, and so on.

The memory 730 may store non-transitory computer-readable media storinginstructions that, when executed by the controller 720, cause the deviceto perform various operations. For example, the controller 720 mayprovide control signals to the projection system 710 (or to one or moreactuators associated therewith) to cause the projection system to switchbetween a 2D mode (e.g., as illustrated in FIG. 2A, 4A, or 6A) and a 3Dmode (e.g., as illustrated in FIG. 2B, 4B, or 6B). The controller 720may provide control signals to the projection system 710 to control thelight-emitting elements thereof to emit light in accordance with imagedata stored in the memory 730 and/or received via communications and I/Ocircuitry 740. Additionally or alternatively, the controller 720 mayprovide control signals to one or more SLMs associated with theprojection system 710 to modify emitted light in accordance with theimage data, thereby to form a projected image on a screen 760.

Moreover, while FIG. 7 illustrates a single device 700 including all ofthe above-noted elements, in some implementations a portion or all ofthe projection system 710 may be separate from the device 700 (e.g., ina separate housing in communication with the device 700). In oneexample, the portions of the projection system 510 associated with theemission of light (e.g., the first laser light source 100L and secondlaser light source 100R of FIG. 1 , the laser light source 300 of FIG. 3, or the laser light source 500 of FIG. 5 ) are disposed in a commonhousing with device 700 whereas the optically-downstream components(e.g., the projectors 120L and 120R of FIG. 1 , the projectors 320L and320R of FIG. 3 , or the projectors 520L and 520R of FIG. 5 ) areprovided in a separate housing or housings in optical and/or electroniccommunication with the device 700. In another example, the entirety ofthe projection system 710 is disposed in a separate housing in opticaland/or electronic communication with the device 700.

Within the projection system 710, various optical fibers may be used todirect light in one or more of the manners described above. In someexamples, the dimensions of the individual optical fibers may beselected so as to reduce or eliminate path differences between variousoptical paths. For example, light may be transported within and/or amongthe projectors by various lengths of 50-800 μm fibers.

Effects and Applications

The above-described optical switch configurations, whether in a combinerimplementation or a splitter implementation, results in the overlappingof the beams before launching into the projection optics. This ensuresuniform illumination. The left-eye RGB wavelength set and the right-eyeRGB wavelength set fiber outputs may be spatially combined, and there isno requirement that the outputs overlap before launching into theprojector, although such a configuration may introduce some decrease inillumination uniformity. Moreover, the spatial overlapping of the beamsallows for sets of lasers with identical spectra to be combined. Two ormore sets of right or left-eye wavelength sets can be combined to createhigher power configurations.

The above description has been particularly described with respect tothe case where the projection system operates using a spectralseparation technique. That is, the above projection systems utilize aleft laser source which emits light with three peaks (one in the redwavelength range, one in the green wavelength range, and one in the bluewavelength range) and a right laser light source which also emits lightwith three peaks (one in the red wavelength range, one in the greenwavelength range, and one in the blue wavelength range), where the peaksin light corresponding to the left eye are spectrally separated from thepeaks in light corresponding to the right eye. In other words, the peakswithin each wavelength range generated by the left laser light sourcemay be shorter in wavelength than the peaks within each wavelength rangegenerated by the right laser light source, or vice versa. However, thepresent disclosure is not so limited.

In some examples, the projection systems described herein may operateusing a technique other than spectral separation. In one example, theprojection systems may operate instead using a polarization separationtechnique, in which left-eye light is polarized in a first direction andright-eye light is polarized in a second direction perpendicular to thefirst direction or in which left-eye light is circularly polarized in aclockwise direction and right-eye light is circularly polarized in acounterclockwise direction (or vice versa).

The systems and methods described herein are comparatively simple and,by design, eliminate any double image artifact (i.e., keystoneartifacts) resulting from two-projector 2D operation. Moreover, thepresent disclosure may reduce or eliminate the need for periodicalignment adjustments due to minor mechanical or thermal movements thatwould be present in comparative example systems.

Systems and devices in accordance with the present disclosure may takeany one or more of the following configurations.

(1) A projection system, comprising: a first light source configured toemit a first-eye light, wherein the first-eye light includes a first setof wavelengths; a second light source configured to emit a second-eyelight, wherein the second-eye light includes a second set ofwavelengths; a first projector including first projection opticsconfigured to receive a first input light; and an optical switchconfigured to be switched between an a first mode and a second mode,wherein the optical switch is configured to, in the first mode, combinethe first-eye light and the second-eye light into a combined light anddirect the combined light to the first projection optics as the firstinput light.

(2) The projection system according to (1), further comprising: a secondprojector including second projection optics configured to receive asecond input light, wherein the optical switch is configured to, in thesecond mode, direct the first-eye light to the second projection opticsas the second input light.

(3) The projection system according to (2), wherein the secondprojection optics includes a spatial light modulator configured toperform a spatial modulation on the second input light in response to animage data, thereby to generate a first-eye projection image when theoptical switch is in the second mode.

(4) The projection system according to any one of (1) to (3), whereinthe optical switch is configured to, in the second mode, direct thesecond-eye light to the first projection optics as the first inputlight.

(5) The projection system according to any one of (1) to (4), whereinthe optical switch includes a reflective element and a first filter, andwhen the optical switch is in the first mode: the reflective element isconfigured to reflect the first-eye light to the first filter asfirst-eye reflected light, and the first filter is configured to reflecta first portion of the second-eye light, to transmit a second portion ofthe second-eye light as a first portion of the combined light, and toreflect the first-eye reflected light as a second portion of thecombined light.

(6) The projection system according to (5), further comprising: a secondprojector including second projection optics configured to receive asecond input light, wherein, when the optical switch is in the secondmode: the reflective element is configured to allow the first-eye lightto pass to the second projector.

(7) The projection system according to (6), wherein the second projectorincludes a second filter configured to, when the optical switch is inthe second mode, reflect a first portion of the first-eye light andtransmit a second portion of the first-eye light as the second inputlight.

(8) The projection system according to any one of (1) to (7), whereinthe first projection optics includes a spatial light modulatorconfigured to perform a spatial modulation on the first input light inresponse to an image data, thereby to generate a second-eye projectionimage when the optical switch is in the second mode and to generate acombined projection image when the optical switch is in the first mode.

(9) The projection system according to any one of (1) to (4), whereinthe optical switch includes a first filter and a reflective element, andwhen the optical switch is in the first mode: the first filter isconfigured to allow the first-eye light and the second-eye light to passto the first projection optics as the combined light.

(10) The projection system according to (9), further comprising: asecond projector including second projection optics configured toreceive a second input light, wherein, when the optical switch is in thesecond mode: the first filter is configured to reflect the first-eyelight and a first portion of the second-eye light to the reflectiveelement as first-eye reflected light, and to transmit a second portionof the second-eye light as the first input light, and the reflectiveelement is configured to direct the first-eye reflected light to thesecond projector.

(11) The projection system according to (10), wherein the secondprojector includes a second filter configured to, when the opticalswitch is in the second mode, reflect a first portion of the first-eyereflected light and transmit a second portion of the first-eye reflectedlight as the second input light.

(12) The projection system according to any one of (1) to (11), whereinthe first light source and the second light source are laser lightsources.

(13) A method of image projection comprising: emitting a first-eye lightby a first light source, wherein the first-eye light includes a firstset of wavelengths; emitting a second-eye light by a second lightsource, wherein the second-eye light includes a second set ofwavelengths; receiving a first input light by a first projectorincluding first projection optics; and switching an optical switchbetween an a first mode and a second mode, wherein the optical switch isconfigured to, in the first mode, combine the first-eye light and thesecond-eye light into a combined light and direct the combined light tothe first projection optics as the first input light.

(14) The method according to (13), wherein the optical switch includes areflective element and a first filter, and switching the optical switchto the first mode comprises: moving the reflective element to a firstposition, so as to reflect the first-eye light to the first filter asfirst-eye reflected light, and causing the first filter to reflect afirst portion of the second-eye light, to transmit a second portion ofthe second-eye light as a first portion of the combined light, and toreflect the first-eye reflected light as a second portion of thecombined light.

(15) The method according to (14), further comprising: receiving asecond input light by a second projector including second projectionoptics, wherein switching the optical switch to the second modecomprises: moving the reflective element to a second position, so as toallow the first-eye light to pass to the second projector.

(16) The method according to (15), wherein the second projector includesa second filter, the method further comprising: when the optical switchis in the second mode, reflecting, by the second filter, a first portionof the first-eye light and transmitting, by the second filter, a secondportion of the first-eye light as the second input light.

(17) The method according to (13), wherein the optical switch includes afirst filter and a reflective element, and switching the optical switchto the first mode comprises: moving the first filter to a firstposition, so as to allow the first-eye light and the second-eye light topass to the first projection optics as the combined light.

(18) The method according to (17), further comprising: receiving asecond input light by a second projector including second projectionoptics, wherein switching the optical switch to the second modecomprises: moving the first filter to a second position, so as toreflect the first-eye light and a first portion of the second-eye lightto the reflective element as first-eye reflected light, and to transmita second portion of the second-eye light as the first input light, anddirecting, by the reflective element, the first-eye reflected light tothe second projector.

(19) The method according to (18), wherein the second projector includesa second filter, the method further comprising: when the optical switchis in the second mode, reflecting, by the second filter, a first portionof the first-eye reflected light and transmitting, by the second filter,a second portion of the first-eye reflected light as the second inputlight.

(20) A non-transitory computer-readable medium storing instructionsthat, when executed by a processor of a projection device, cause theprojection device to perform operations comprising the method accordingto any one of (13) to (19).

With regard to the processes, systems, methods, heuristics, etc.described herein, it should be understood that, although the steps ofsuch processes, etc. have been described as occurring according to acertain ordered sequence, such processes could be practiced with thedescribed steps performed in an order other than the order describedherein. It further should be understood that certain steps could beperformed simultaneously, that other steps could be added, or thatcertain steps described herein could be omitted. In other words, thedescriptions of processes herein are provided for the purpose ofillustrating certain embodiments, and should in no way be construed soas to limit the claims.

Accordingly, it is to be understood that the above description isintended to be illustrative and not restrictive. Many embodiments andapplications other than the examples provided would be apparent uponreading the above description. The scope should be determined, not withreference to the above description, but should instead be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled. It is anticipated andintended that future developments will occur in the technologiesdiscussed herein, and that the disclosed systems and methods will beincorporated into such future embodiments. In sum, it should beunderstood that the application is capable of modification andvariation.

All terms used in the claims are intended to be given their broadestreasonable constructions and their ordinary meanings as understood bythose knowledgeable in the technologies described herein unless anexplicit indication to the contrary in made herein. In particular, useof the singular articles such as “a,” “the,” “said,” etc. should be readto recite one or more of the indicated elements unless a claim recitesan explicit limitation to the contrary.

The Abstract of the Disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the claims. In addition, in theforegoing Detailed Description, it can be seen that various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments incorporate morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed embodiment. Thus, the following claimsare hereby incorporated into the Detailed Description, with each claimstanding on its own as a separately claimed subject matter.

What is claimed is:
 1. A projection system, comprising: a first lightsource configured to emit a first-eye light, wherein the first-eye lightincludes a first set of wavelengths; a second light source configured toemit a second-eye light, wherein the second-eye light includes a secondset of wavelengths; a first projector including first projection opticsconfigured to receive a first input light; and an optical switchconfigured to be switched between a first mode and a second mode,wherein the optical switch is configured to, in the first mode, combinethe first-eye light and the second-eye light into a combined light anddirect the combined light to the first projection optics as the firstinput light, wherein the optical switch includes a reflective elementand a first filter, and when the optical switch is in the first mode:the reflective element is configured to reflect the first-eye light tothe first filter as first-eye reflected light, and the first filter isconfigured to reflect a first portion of the second-eye light, totransmit a second portion of the second-eye light as a first portion ofthe combined light, and to reflect the first-eye reflected light as asecond portion of the combined light.
 2. The projection system accordingto claim 1, further comprising: a second projector including secondprojection optics configured to receive a second input light, whereinthe optical switch is configured to, in the second mode, direct thefirst-eye light to the second projection optics as the second inputlight.
 3. The projection system according to claim 2, wherein the secondprojection optics includes a spatial light modulator configured toperform a spatial modulation on the second input light in response to animage data, thereby to generate a first-eye projection image when theoptical switch is in the second mode.
 4. The projection system accordingto claim 1, wherein the optical switch is configured to, in the secondmode, direct the second-eye light to the first projection optics as thefirst input light.
 5. The projection system according to claim 1,further comprising: a second projector including second projectionoptics configured to receive a second input light, wherein, when theoptical switch is in the second mode: the reflective element isconfigured to allow the first-eye light to pass to the second projector.6. The projection system according to claim 5, wherein the secondprojector includes a second filter configured to, when the opticalswitch is in the second mode, reflect a first portion of the first-eyelight and transmit a second portion of the first-eye light as the secondinput light.
 7. The projection system according to claim 1, wherein thefirst projection optics includes a spatial light modulator configured toperform a spatial modulation on the first input light in response to animage data, thereby to generate a second-eye projection image when theoptical switch is in the second mode and to generate a combinedprojection image when the optical switch is in the first mode.
 8. Theprojection system according to claim 1, wherein the first light sourceand the second light source are laser light sources.
 9. A projectionsystem, comprising: a first light source configured to emit a first-eyelight, wherein the first-eye light includes a first set of wavelengths;a second light source configured to emit a second-eye light, wherein thesecond-eye light includes a second set of wavelengths; a first projectorincluding first projection optics configured to receive a first inputlight; an optical switch configured to be switched between a first modeand a second mode; and a second projector including second projectionoptics configured to receive a second input light, wherein the opticalswitch is configured to, in the first mode, combine the first-eye lightand the second-eye light into a combined light and direct the combinedlight to the first projection optics as the first input light, whereinthe optical switch includes a first filter and a reflective element,wherein, when the optical switch is in the first mode: the first filteris configured to allow the first-eye light and the second-eye light topass to the first projection optics as the combined light, and wherein,when the optical switch is in the second mode: the first filter isconfigured to reflect the first-eye light and a first portion of thesecond-eye light to the reflective element as first-eye reflected light,and to transmit a second portion of the second-eye light as the firstinput light, and the reflective element is configured to direct thefirst-eye reflected light to the second projector.
 10. The projectionsystem according to claim 9, wherein the second projector includes asecond filter configured to, when the optical switch is in the secondmode, reflect a first portion of the first-eye reflected light andtransmit a second portion of the first-eye reflected light as the secondinput light.
 11. A method of image projection comprising: emitting afirst-eye light by a first light source, wherein the first-eye lightincludes a first set of wavelengths; emitting a second-eye light by asecond light source, wherein the second-eye light includes a second setof wavelengths; receiving a first input light by a first projectorincluding first projection optics; and switching an optical switchbetween a first mode and a second mode, wherein the optical switch isconfigured to, in the first mode, combine the first-eye light and thesecond-eye light into a combined light and direct the combined light tothe first projection optics as the first input light, wherein theoptical switch includes a reflective element and a first filter, andswitching the optical switch to the first mode comprises: moving thereflective element to a first position, so as to reflect the first-eyelight to the first filter as first-eye reflected light, and causing thefirst filter to reflect a first portion of the second-eye light, totransmit a second portion of the second-eye light as a first portion ofthe combined light, and to reflect the first-eye reflected light as asecond portion of the combined light.
 12. The method according to claim11, further comprising: receiving a second input light by a secondprojector including second projection optics, wherein switching theoptical switch to the second mode comprises: moving the reflectiveelement to a second position, so as to allow the first-eye light to passto the second projector.
 13. The method according to claim 12, whereinthe second projector includes a second filter, the method furthercomprising: when the optical switch is in the second mode, reflecting,by the second filter, a first portion of the first-eye light andtransmitting, by the second filter, a second portion of the first-eyelight as the second input light.
 14. A method of image projectioncomprising: emitting a first-eye light by a first light source, whereinthe first-eye light includes a first set of wavelengths; emitting asecond-eye light by a second light source, wherein the second-eye lightincludes a second set of wavelengths; receiving a first input light by afirst projector including first projection optics; and switching anoptical switch between a first mode and a second mode, wherein theoptical switch is configured to, in the first mode, combine thefirst-eye light and the second-eye light into a combined light anddirect the combined light to the first projection optics as the firstinput light, wherein the optical switch includes a first filter and areflective element, and switching the optical switch to the first modecomprises: moving the first filter to a first position, so as to allowthe first-eye light and the second-eye light to pass to the firstprojection optics as the combined light.
 15. The method according toclaim 14, further comprising: receiving a second input light by a secondprojector including second projection optics, wherein switching theoptical switch to the second mode comprises: moving the first filter toa second position, so as to reflect the first-eye light and a firstportion of the second-eye light to the reflective element as first-eyereflected light, and to transmit a second portion of the second-eyelight as the first input light, and directing, by the reflectiveelement, the first-eye reflected light to the second projector.
 16. Themethod according to claim 15, wherein the second projector includes asecond filter, the method further comprising: when the optical switch isin the second mode, reflecting, by the second filter, a first portion ofthe first-eye reflected light and transmitting, by the second filter, asecond portion of the first-eye reflected light as the second inputlight.
 17. A non-transitory computer-readable medium storinginstructions that, when executed by a processor of a projection device,cause the projection device to perform a set of operations comprising:controlling a first light source to emit a first-eye light, wherein thefirst-eye light includes a first set of wavelengths; controlling asecond light source to emit a second-eye light, wherein the second-eyelight includes a second set of wavelengths; controlling a firstprojector to receive a first input light, the first projector includingfirst projection optics; and controlling an optical switch to switchbetween a first mode and a second mode, wherein the optical switch, inthe first mode, combines the first-eye light and the second-eye lightinto a combined light and directs the combined light to the firstprojection optics as the first input light, wherein the optical switchincludes a reflective element and a first filter, and controlling theoptical switch to switch to the first mode comprises: controlling thereflective element to move to a first position, so as to reflect thefirst-eye light to the first filter as first-eye reflected light, andcausing the first filter to reflect a first portion of the second-eyelight, to transmit a second portion of the second-eye light as a firstportion of the combined light, and to reflect the first-eye reflectedlight as a second portion of the combined light.
 18. A non-transitorycomputer-readable medium storing instructions that, when executed by aprocessor of a projection device, cause the projection device to performa set of operations comprising: controlling a first light source to emita first-eye light, wherein the first-eye light includes a first set ofwavelengths; controlling a second light source to emit a second-eyelight, wherein the second-eye light includes a second set ofwavelengths; controlling a first projector to receive a first inputlight, the first projector including first projection optics; andcontrolling an optical switch to switch between a first mode and asecond mode, wherein the optical switch, in the first mode, combines thefirst-eye light and the second-eye light into a combined light anddirects the combined light to the first projection optics as the firstinput light, wherein the optical switch includes a reflective elementand a first filter, and wherein controlling the optical switch to switchto the first mode comprises: controlling the reflective element to movethe first filter to a first position, so as to allow the first-eye lightand the second-eye light to pass to the first projection optics as thecombined light.